Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in JAVA):

Solution:
import java.util.*;
import java.text.*;

public class Main {

    Scanner sc = new Scanner(System.in);

    int h = sc.nextInt();
    int w = sc.nextInt();
    char[][] arr = new char[h][w];
    int[][] d = new int[h][w];
    int[] dx = {1, 0, -1, 0};
    int[] dy = {0, 1, 0, -1};

    public static void main(String[] args){
        new Main().run();
    }

    void run() {

        for (int i=0; i<h; i++) {
            arr[i] = sc.next().toCharArray();
        }

        int wallCnt = 0;

        for (int i=0; i<h; i++) {
            for (int j=0; j<w; j++) {
                d[i][j] = Integer.MAX_VALUE;
                if (arr[i][j] == '#') wallCnt++;
            }
        }
        d[0][0] = 0;

        dfs(new Pair(0, 0));

        if (d[h-1][w-1] == Integer.MAX_VALUE) {
            System.out.println(-1);
        } else {
            System.out.println(h * w - wallCnt - d[h-1][w-1] - 1);
        }
    }

    void dfs(Pair pair) {

        Queue<Pair> queue = new ArrayDeque<>();
        queue.add(pair);
        while (!queue.isEmpty()) {
            Pair tmp = queue.peek();
            for (int i=0; i<4; i++) {
                int ny = tmp.y + dy[i];
                int nx = tmp.x + dx[i];
                if (ny<0 || h<=ny || nx<0 || w<=nx) continue;
                if (arr[ny][nx] == '#') continue;
                if (d[ny][nx] != Integer.MAX_VALUE) continue;
                d[ny][nx] = Math.min(d[ny][nx], d[tmp.y][tmp.x]+1);
                queue.add(new Pair(ny, nx));
            }
            queue.poll();
        }

    }

    class Pair {
        int y;
        int x;
        public Pair(int y, int x) {
            this.y = y;
            this.x = x;
        }
    }

}